This invention relates to a method of welding to the exterior of a metal tank or similar body, a projecting metal part, such as a supporting bracket for the tank, and, more particularly, relates to a welding method which: (a) lends itself to use with a supporting bracket of an inexpensive design and (b) produces a high strength joint that requires no additional material other than paint to effectively resist joint-corrosion. The invention also relates to a joint made by this method.
My invention is especially applicable to electrical apparatus which comprises a cylindrical steel tank and a steel supporting bracket of U-shaped cross-section welded to the exterior of the tank for supporting the tank in an outdoor location where corrosion at the welded joint can be a problem. A typical U-shaped bracket for such applications comprises spaced-apart legs projecting generally radially toward the tank wall and flanges at the inner ends of legs that conform in shape to the exterior surface of the tank and are projection welded to the tank wall. To project such welded joints from corrosion, a number of different procedures have been used. For example, the parts have sometimes been plated, or special sealants have been provided around the entire outer perimeter of each flange, or an arc weld has been applied around this perimeter for sealing and reinforcing purposes. In some cases, paint alone has been provided around the perimeter of each flange, but this approach has not been as reliable as might be desired since this necessitates relying upon the projection welds alone for providing the mechanical strength of the joint and, moreover, there may sometimes be insufficient conformity between the flange surface and the juxtaposed tank surface for the paint to provide an effective and durable steel between these surfaces.
Another disadvantage of the above-described methods is that they require flanges at the inner ends of the bracket legs and, particularly, flanges of a shape to conform with the tank exterior. Such flanges are relatively expensive since their presence necessitates extra material and extra forming steps.